PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Auditory Threshold”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
PubMed1992

Threshold estimation using the "chained stimuli" auditory brain stem response technique.

The chained stimuli ABR method, which allows acquisition of data for a seven-point latency-intensity function for both ears in approximately 35 min, is described. Testing of 22 ears with a simulated conductive loss, and 20 ears with sensorineural impairment, indicates that the chained stimuli method provides equivalent threshold estimates to that obtained with the conventional ABR measurement technique.

Acoustic Impedance Tests↗
PubMed1986

Methods for determining auditory evoked brain-stem response thresholds in human newborns.

Previous investigators have reported that newborn auditory evoked brain-stem responses (ABRs) are 20-30 dB higher than adult psychophysical thresholds to the same stimuli. These investigators reduced the intensity of the stimulus until they no longer reported an ABR to the stimulus. We adapted 2 widely used psychophysical methods, the up-down-transformed response (UDTR) method and the method of constant stimuli, for ABR threshold determination of human newborns. Response judgments were made blindly. ABR thresholds of healthy normal newborns by both procedures were no more than 10-15 dB higher than adult psychophysical thresholds. The differences between the newborn ABR thresholds we reported and those in the literature were probably explained by different procedures including the method used to estimate adult psychophysical thresholds. The correlations between ABR thresholds and suprathreshold ABR latencies and amplitudes and latency and amplitude/intensity functions were modest at best. In normal newborns suprathreshold ABR measurements are of little value in predicting ABR thresholds.

Brain Stem↗
PubMed1986

Frequency selectivity of hearing in the green treefrog, Hyla cinerea.

Frequency selectivity of hearing was measured in the green treefrog, Hyla cinerea. A psychophysical technique based on reflex modification was used to obtain masked threshold estimates for pure tones (300-5,400 Hz) presented against two levels of broadband masking noise. A pure tone (S-1) presented 200 ms prior to a reflex-eliciting stimulus (S-2) inhibited the motor reflex response to S-2. The magnitude of this reflex modification effect varied systematically with the sound pressure level (SPL) of S-1, and threshold was defined as the SPL of S-1 at which the reflex modification effect disappeared. Masked thresholds were used to calculate critical ratios, an index of the auditory system's frequency selectivity. The frequency selectivity of the treefrog's hearing is greatest and critical ratios are lowest (22-24 dB) at about 900 and 3,000 Hz, the two spectral regions dominant in the male treefrog's species-specific advertisement call. These results suggest that the treefrog's auditory system may be specialized to reject noise at biologically-relevant frequencies. As in other vertebrates, critical ratios remain constant when background noise level is varied; however, the shape of the treefrog's critical ratio function across frequencies differs from the typical vertebrate function that increases with increasing frequency at a slope of about 3 dB/octave. Instead, the treefrog's critical ratio function resembles its pure tone audiogram. Although the shape of the treefrog's critical ratio function is atypical, the critical ratio values themselves are comparable to those of many other vertebrates in the same frequency range. Critical ratio values here measured behaviorally do not match critical ratio values previously measured physiologically in single eighth nerve fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMedDate not supplied

Early tone-evoked responses in normal and hearing-impaired subjects.

Early evoked responses to 500-Hz tone bursts were recorded from normal and hearing-impaired children and adults. The threshold values of the early evoked responses provide useful estimates of auditory functioning, even among difficult-to-test populations, such as deaf-blind children. Latency measures indicate that the early response is generated at the brain stem. Latency measures from hearing-impaired subjects show that the response can identify recruitment. Several subjects having a history of nonspecific communication disorders, e.g., dyslexia, exhibited aberrant early evoked response waveforms. The early-evoked response measures, therefore, amy be useful in detecting and assessing communication disorders which are believed to be of cortical origin, but now should be considered to have a basis in brain stem dysfunction.

Acoustic Stimulation↗
PubMed2006

Sound-evoked myogenic potentials on the sternocleidomastoid muscle in monkeys.

CONCLUSION: We recorded sound-evoked myogenic potentials of the sternocleidomastoid (SCM) muscle using awake monkeys. The characteristics of these potentials are similar to those of vestibular evoked myogenic potentials (VEMPs) in humans, suggesting that the sound-evoked myogenic potentials of the SCM muscle in monkeys may be utilized as an animal model of VEMPs. OBJECTIVE: The pathway of the VEMPs remains uncertain as no animal model has yet been used to record sound-evoked myogenic potentials in the SCM muscle. Therefore, the present study aimed to establish an animal model of VEMPs using macaque monkeys. MATERIALS AND METHODS: Four macaque monkeys were used. A pair of electrodes was attached on the SCM muscle ipsilateral side to the intense sound stimulation. RESULTS: The sound-evoked myogenic potentials of the SCM muscle exhibited a biphasic waveform. When a click at 125 dBSPL was applied, the peak latency of the first positive wave was 12.5 ms and was not delayed when the stimulating sound intensity was reduced. The thresholds of the myogenic potentials were 103 dBSPL, which were 43 dB higher than those of the auditory brainstem response (ABR). When a short tone burst was applied, the reactive optimal frequency of the myogenic potentials was relatively low (500-1000 Hz).

Acoustic Stimulation↗
PubMed2002

Infant discrimination of rapid auditory cues predicts later language impairment.

The etiology and mechanisms of specific language impairment (SLI) in children are unknown. Differences in basic auditory processing abilities have been suggested to underlie their language deficits. Studies suggest that the neuropathology, such as atypical patterns of cerebral lateralization and cortical cellular anomalies, implicated in such impairments likely occur early in life. Such anomalies may play a part in the rapid processing deficits seen in this disorder. However, prospective, longitudinal studies in infant populations that are critical to examining these hypotheses have not been done. In the study described, performance on brief, rapidly-presented, successive auditory processing and perceptual-cognitive tasks were assessed in two groups of infants: normal control infants with no family history of language disorders and infants from families with a positive family history for language impairment. Initial assessments were obtained when infants were 6-9 months of age (M=7.5 months) and the sample was then followed through age 36 months. At the first visit, infants' processing of rapid auditory cues as well as global processing speed and memory were assessed. Significant differences in mean thresholds were seen in infants born into families with a history of SLI as compared with controls. Examination of relations between infant processing abilities and emerging language through 24 months-of-age revealed that threshold for rapid auditory processing at 7.5 months was the single best predictor of language outcome. At age 3, rapid auditory processing threshold and being male, together predicted 39-41% of the variance in language outcome. Thus, early deficits in rapid auditory processing abilities both precede and predict subsequent language delays. These findings support an essential role for basic nonlinguistic, central auditory processes, particularly rapid spectrotemporal processing, in early language development. Further, these findings provide a temporal diagnostic window during which future language impairments may be addressed.

Apgar Score↗
PubMed1988

Protection against noise trauma by pre-exposure to a low level acoustic stimulus.

Guinea pigs were pre-exposed to a low level acoustic stimulus prior to exposure to a stimulus known to yield a permanent threshold shift. This pre-treatment resulted in: 1) approximately a 20 dB reduction in the threshold shift relative to animals not pre-exposed, and 2) complete recovery from the threshold shift after 2 months.

Acoustic Stimulation↗
PubMed1983

Response patterns of auditory nerve fibers during temporary threshold shift.

Temporary threshold shifts were studied in chinchillas exposed to noise (octave-band noise centered at 500 Hz, 95 dB SPL, 5 days duration) and the response properties of their auditory nerve fibers were measured. The threshold shifts of the fibers were approximately 35 to 65 dB; these values were equal to or slightly greater than those measured behaviorally. Most units had broad V-shaped tuning curves due to a greater loss in sensitivity near the characteristic frequency (CF) than in the low-frequency tail. In 17% of the units, the thresholds were actually lower in the tail than at CF, so that the tuning curves were W-shaped. The latencies of the fibers were within normal limits in terms of absolute intensity, but shorter than normal in terms of intensity relative to threshold. Other measures such as the spontaneous discharge rate, the discharge rate-intensity functions, and the firing patterns to tone bursts at CF appeared normal. These results indicate that neural response patterns during noise-induced temporary threshold shift are similar to those measured during permanent threshold shift.

Action Potentials↗
PubMed1995

Effect of hypoxemia and ethacrynic acid on ABR and distortion product emission thresholds.

Various studies have shown that induction of hypoxemia in animals such that arterial blood oxygen tensions reach 20-30 mm Hg is accompanied by reversible threshold elevations of the auditory nerve-brain-stem evoked response (ABR). In this state, the endocochlear potential (EP) is depressed, causing a smaller potential difference across the hair cells and/or reduced activity of the cochlear amplifier of the outer hair cells. In order to test these possibilities, ABR threshold (an expression of the overall sensitivity of the cochlea) and changes in threshold of the cubic (2f1-f2) distortion product emissions (DPE) (an expression of activity of the cochlear amplifier) were measured in the same cats while the EP was depressed by hypoxemia or by ethacrynic acid. During the episodes of hypoxemia, DPE thresholds were elevated by 10 dB while ABR thresholds were elevated by 22.8 dB. Therefore, it seems that a normal EP is necessary both for normal cochlear transduction (inner hair cells) and for normal cochlear amplification (outer hair cells). The human fetus in utero is relatively hypoxic and there is evidence that its auditory threshold is also similarly elevated. Therefore the threshold elevation in the fetus in utero, estimated to be about 20 dB, is a consequence of both reduced transduction current through the inner hair cells (about 10 dB) and an additional 10 dB reduction in the activity of the cochlear amplifier of the outer hair cells.

Animals↗
PubMed2002

[Steady state multi-frequency auditory evoked potentials as a technique to determine hearing threshold].

OBJECTIVE: Since the set up of Steady-State Auditory Evoked Potentials as a routine technique, it has became necessary the establishment of clinic capabilities and limitations. In this study, we have compared SSEP to behavioural thresholds, considering the last one as "gold standard" technique. MATERIALS AND METHODS: We have recorded SSEP to multiple frequencies and behavioural thresholds in 84 ears. The obtained data were statistically processed to obtain correlations and others indicators. RESULTS: SSEP thresholds are slightly higher than behavioural, whose average difference was calculated as 23 dB. It is worth to note that this difference diminishes at high frequencies and hearing loss cases. CONCLUSIONS: SSEP to multiple frequencies technique is capable to determine auditory thresholds accurately, being closer to the behavioural value at high frequencies and high threshold values. It is necessary the establishment of exploration protocols to assure the highest accuracy of the system. In this work, a diagnostic algorithm has been proposed to reach better results by using SSEP.

Adolescent↗
PubMed1991

Development of otoacoustic emissions in gerbil: evidence for micromechanical changes underlying development of the place code.

The development of the acoustic distortion product (ADP) 2f1-f2 was studied in gerbils, beginning 12 days after birth (P12). ADPs were measured as a function of stimulus frequency region (1.0 to 13.0 kHz) and level (10 to 80 dB SPL). There was an orderly progression in the appearance and maturation of the emissions, with responses to high-frequency stimuli (f2 = 13.0 kHz) appearing first, at P13-14. Responses to mid and high frequencies (f2 = 3.9 to 13.0 kHz) matured earlier than responses to lower frequencies. Responses to low-frequency stimuli (f2 = 1.3 KHz) did not appear until P18-19 and were not mature until after one month of age. The first emissions to develop in a given frequency region had elevated thresholds, were reduced in amplitude, and displayed monotonic input-output functions. As the auditory system matured, emission growth functions became non-monotonic displaying saturation, but initially retained a reduced dynamic range. Data from the developing gerbil suggest that initially its cochlear mechanics are passive and that active elements associated with normal outer hair cell function mature first in the basal turn and last near the apex. Furthermore, the development of active nonlinear elements underlying ADP generation is consistent with the development of frequency selectivity and developmental shifts in the place code which have been demonstrated in the gerbil.

Acoustic Stimulation↗
PubMed2006

Audiometry with nasally presented masking noise: novel diagnostic method for patulous eustachian tube.

OBJECTIVE: Nasal-noise masking audiometry was developed to assess the acoustic transfer function from the nasopharyngeal cavity to the middle ear via patulous eustachian tube (ET). STUDY DESIGN: Prospective. SETTING: Tertiary referral center. PATIENTS: Twenty-seven ears of 18 patients with patulous ET and 20 ears of 10 healthy subjects with no history of ear disease or complaints of aural symptoms. MAIN OUTCOME MEASURES: Audiometric measurement was conducted with and without masking noise presented in the nasal cavity. RESULTS: The masking effect of nasally presented noise caused elevation of the threshold for the tone presented in the external auditory canal. This threshold elevation was significantly greater, particularly in the lower-frequency region, in ears with patulous ET and was decreased to the normal range after obstructive treatment of the patulous ET. CONCLUSION: Nasal-noise masking audiometry is a simple and effective way to identify patulous ET.

Acoustic Stimulation↗